1. Field of the Invention
Exemplary embodiments of the present invention relate to a radio repeater apparatus and system, and an operating method thereof; and, more particularly, to a radio repeater apparatus and system, which is capable of strengthening a repeating target base station signal (target base station signal) among various base station signals which are mixed and received, and suppressing the other base station signals to reduce interference between the base station signals, in order to improve the repeating quality of downlink signals, and an operating method thereof.
2. Description of Related Art
In general, a radio repeater system is a system which receives and amplifies a downlink signal transmitted from a radio base station to a radio terminal or an uplink signal transmitted from a radio terminal to a radio base station and then transmits the amplified signal. The radio repeater system, is installed in the transmission section of the radio base station, in order to expand a service area and provide a smooth service to a radio shadow area.
At this time, in a cell-edge area or a base station-dense area in downtown, a donor antenna of a radio repeater system installed toward a target base station may not only receive a signal of the target base station, but may receive signals of other base stations. Such a phenomenon may occur in signals received by radio terminals. The signals received from the other base stations serve as interference signals which may cause radio interference when the same radio resource is used, and degrade the quality of the signals received by the terminals due to a frequency error between the respective base stations.
FIG. 1 is a configuration diagram of a conventional radio repeater system, illustrating the concept that the radio repeater system is operated in a base station interference environment.
Referring to FIG. 1, the conventional radio repeater system includes a donor antenna 103, a radio repeater apparatus 104, and a service antenna 105. The donor antenna 103 is configured to transmit/receive a signal to/from a base station. The radio repeater apparatus 104 is configured to amplify and repeat a base station signal and a terminal signal, which are inputted through the donor antenna 103 and the service antenna 105, respectively. The service antenna 105 is configured to transmit/receive a signal to/from a radio terminal in a service area.
In general, the radio repeater system is installed at positions at which the interference between base station signals frequently occurs. Thus, the donor antenna 103 may not only receive a signal of a target base station 100, but also receive signals of other base stations 101 and 102. At this time, the radio repeater system not only amplifies and transmits the signal of the target base station 100, but also amplifies and transmits the signals of the other base stations 101 and 102, which serve as interference signals. In this case, since the signal quality of the service area is degraded, the installation effect of the radio repeater system may not be obtained.
Furthermore, the frequency use efficiency of multiple input multiple output (MIMO) signals may be increased when signals passing through different channels have low correlation in a multi-path environment. However, the conventional radio repeater system operates according to a single input single output (SISO) system including one donor antenna 103 and one service antenna 105. Thus, although the base station operates according to the MIMO system, a signal repeated through the radio repeater system may not be distinguished from signals in different channel environments. In this case, the operation effect of the radio repeater system may not be obtained.
Furthermore, when isolation between the donor antenna 103 and the service antenna 105 is not sufficiently secured, a signal of the service antenna 105 may be introduced to the donor antenna 103 of the radio repeater system. That is, a feedback interference signal may be introduced. In this case, since the gain of the radio repeater system cannot be increased to inevitably reduce the coverage of the service area, the efficiency of the radio repeater system may decrease.
Therefore, the conventional radio repeater system has disadvantages in that the repeating quality of downlink signals is degraded, the frequency use efficiency is decreased, and the stability of repeated signals is reduced.